Abstract: To select a designated bottle in a sampler, the distributor is calibrated as to position and the outlet of the distributor arm is moved over the desired bottle by counting changes in incremental angular movement of the distributor arm until it is over the bottle. The position of the distributor arm is recorded in memory. To calibrate the distributor, the arm is rotated against a stop member in a first direction, then in a second direction and the overrun of in excess of 360 degrees of the motion of the distributor arm is determined and corrected. A series of random numbers is generated for depositing of samples, the distributor is moved at designated times over the bottles in a random order to deposit a sample and the ordering of bottles is recorded. The rollers of a peristaltic pump are supported to prevent said rollers from compressing said tube more than the thickness of the walls of the tube. A functional module for a bubbler or pH probe or ultrasonic level detector may be connected to the housing.

Abstract: To determine the average velocity of a fluid stream, an ultrasonic signal is transmitted into the fluid and reflected ultrasonic signal received. The signals are mixed with a frequency of the transmitted ultrasonic signals. A Fourier transform is performed on the signals, the largest coefficient used to normalize the signal and certain of the weighted signals are averaged.

Abstract: To determine the average velocity of a fluid stream, an ultrasonic signal is transmitted into the fluid and reflected ultrasonic signal received. The signals are mixed with a frequency of the transmitted ultrasonic signals. A Fourier transform is performed on the signals, the largest coefficient used to normalize the signal and certain of the weighted signals are averaged.

Abstract: To measure flow rates, the cross-sectional shape of the flow path is changed by inserting a multiple position gate into the flow path and altering the position of the gate to maintain the head of liquid constant with a reduced flow cross section. To maintain the head at a desirable range, the depth is measured and controls the position of the gate as a feedback signal. The position of the multiple position gate is correlated with the depth to provide an indication of flow rate. For this purpose, a flow path housing is clamped to a pipe and a multiple position gate is moved by pneumatic pressure into the flow stream to change the flow cross section. The depth of the head upstream of the gate is measured and the position of the gate is measured. Flow rate is determined from these two measurements. Sampling may be performed at an increased depth caused by the gate.